Path: xname,
		Args: []string{"ip", "address", "add", ti.local, "peer", ti.remote, "dev", ti.name},
	})
	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
		Path: xname,
		Args: []string{"ip", "address", "del", ti.local, "peer", ti.remote, "dev", ti.name},
	})
	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
		Path: xname,
		Args: []string{"ip", "link", "delete", ti.name, "type", "dummy"},
	})
	return nil
}

	xname, err := exec.LookPath("ifconfig")
	if err != nil {
		return err
	}
	ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
		Path: xname,
		Args: []string{"ifconfig", ti.name, "create"},
	})
	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
		Path: xname,
		Args: []string{"ifconfig", ti.name, "destroy"},
	})
	return nil
}

func (ti *testInterface) setPointToPoint(suffix int) error {
	ti.name = fmt.Sprintf("gif%d", suffix)

	remote       string
	setupCmds    []*exec.Cmd
	teardownCmds []*exec.Cmd
}

func (ti *testInterface) setup() error {
	for _, cmd := range ti.setupCmds {
		if out, err := cmd.CombinedOutput(); err != nil {
			return fmt.Errorf("args=%v out=%q err=%v", cmd.Args, string(out), err)
		}
	}
	return nil
}

func (ti *testInterface) teardown() error {
	for _, cmd := range ti.teardownCmds {